In time division duplexed (TDD) systems, some portions of a frame are reserved for carrying downlink transmissions, while other portions of a radio frame are reserved for carrying uplink transmissions. In some systems, the apportionment of uplink and downlink portions (referred to herein as the uplink-downlink (UL/DL) configuration) of a frame may be configured semi-statically or dynamically, so that UL/DL configuration may be adapted to changing network conditions.
The rate in which the UL/DL configuration is updated (or changed) may vary from network to network. For instance, third generation partnership (3GPP) long term evolution (LTE) release eleven (rel-11) networks may update the UL/DL configuration once every 640 milliseconds (ms), while 3GPP LTE release twelve (rel-12) networks may update the UL/DL configuration more often (e.g., as often as every 10 ms). As a result, base stations (eNBs) and User Equipments (UEs) adapted for 3GPP LTE rel-12 (referred to herein next-generation eNBs and UEs) may update the UL/DL configuration more often than UEs adapted for 3GPP LTE rel-11 and prior releases (referred to herein as legacy UEs) detect UL/DL configuration updates. For instance, next-generation eNBs may update the UL/DL configuration every 10 or 20 ms, while legacy UEs may only detect updates to the UL/DL configuration every 640 ms. Consequently, legacy UEs being served by next-generation eNBs may be incapable of recognizing some updates to the UL/DL configuration.